Ball actuated inertia switch

ABSTRACT

Inertia switch with mass freely movable in chamber and energizing switch means upon reception in chamber.

United States Patent 11 1 Bell et a1.

1 1 BALL ACTUATED INERTIA SWITCH Inventors: Lon E. Bell; William B.Gruber,

both of Altadena, Calif.

Assignee: Technar, Incorporated, Pasadena,

Calif.

Filed: Aug. 23, 1972 Appl. No: 283,243

US. Cl.... ZOO/61.45 R, 200/61.52, ZOO/DIG. 2 Int. Cl. H0111 35/14,l-lOlh 1/16 Field of Search ZOO/DIG. 29, 61.11, 61.41,

ZOO/61.42, 61.43, 61.45 R, 61.48, 61.52

References Cited UNITED STATES PATENTS 11/1912 Myers 200/D1G. 29

[451 May 21, 1974 3,644,921 2/1972 Duggan et a1 ZOO/61.45 R X 1,662,9793/1928 Nelson ZOO/DIG. 29

FOREIGN PATENTS OR APPLICATIONS 1,088,079 9/1954 France ZOO/61.11

Primary ExaminerJames R. Scott Attorney, Agent, or Firm-Jonathan Plaut 57] ABSTRACT Inertia switch with mass freely movable in chamber andenergizing switch means upon reception in chamber.

3 Claims, 4 Drawing Figures BALL ACTUATED INERTIA SWITCH This inventionrelates to a G switch which embodies a mass removably mounted at thebase of inclined apertured structure for biasing electrical contactmeans in one position when stationed partially within said aperture, andin a second position when said mass has moved from said aperture and ison the incline as a result of certain G forces.

Generally, the invention comprises a spherical mass or ball, in oneembodiment, freely mounted for movement within a cylinder having anapertured inclined base. On the under-surface of the base is a contactwire biased into a position near the base which, when engaged by thespherical mass located within the aperture, moves to a position toengage another contact wire and implement the function of the switch.

When subjected to G forces of a certain predetermined level or greater,as a result of acceleration or deceleration, the mass moves from theapertured base up the incline and loses contact with the spring wireunderneath the base. The fact that the spherical mass at a rest positionis within the aperture and must first escape fromthe aperture provides apositive acting go:- no-go condition. The factor of escape from theaperture and that the mass must move up an incline on escaping theaperture under G forces, provides for not only positive action, but thefiltering of those forces acting on the switch which are short durationpulses, as will be discussed later hereinafter. Since the contact wireagainst which the spherical mass abuts does lie against the mass untilit moves from the aperture and a certain distance up the incline, suchfiltering effect is substantial.

The diameter of the aperture in the base in which the mass rests and theangle of incline determines the level of G forces needed to get and keepthe spherical mass out of the apertured base and on the incline and thusout of contact with the contact wire.

In the usage of the sensor, the cylinder containing the mass is of suchheight that the mass may escape the aperture and incline entirely whenthe sensor is inverted, such as by a rollover of an automobile, to breakcontact with the contact wire.

The invention will now be described in more detail and furtheradvantages understood with respect to the following drawings.

FIG. 1 shows the ball in rest position in one embodiment of the sensor;

FIG. 2 shows an end view of FIG. 1;

FIG. 3 shows the sensor of FIG. 1 with the mass having escaped theapertured base and on the incline thereof; and

FIG. 4 shows a second embodiment of the invention.

In the embodiment of FIG. 1 is shown a cylindrical casing 2 of aninertia sensor 1. Freely movable about within the casing, which forms achamber 70, is a spherical mass or ball 3 which is held within thecasing by its side wall 30, a base 4 integral therewith and a top 5mounted on the side walls. The base 4 is inclined interior of the casingat an upward angle toward the side wall of the casing 2. The sphericalmember, when it rests, sits within the aperture or hole 7 in the base 4and between the inclines 14 and extends therethrough at the bottom.

Mounted on the under surface 6 of the bottom of the base 4 is a springcontact wire 5a which is biased so as to tend to lie close to the base4. The contact wire 5a may be preferably, in one embodiment, mounted ina groove 6 in the underside of the base 4 to enhance contact of the wirewith the ball.

On one side of the aperture or hole 7 is mounted an electrical contactarm 8 which is in electrical contact with the wire 5a (see FIG. 2). Inone embodiment, on the opposite side of the hole 7 from the contact arm8 is a second contact arm 9 which has extending therefrom a contact wire10 mounted so as to over-lie the contact wire 5a. The wire 5a may befastened by welding to the contact arm 8 on the underside of the base at12. In this embodiment, the wire 5a advantageously is free at theopposite end for movement under the influence of the mass 3. The contactwire 10 may be fastened to the base 4 at the end opposite to arm 9, asat 13, and is in electrical contact at the other end with arm 9.

When the spherical mass 3 is located in the hole 7, it bears against thecontact wire 50 and pushes it against its own bias outward (away fromthe base) so as to be in contact with the wire 10 and complete theelectrical circuit from the arm 8, through the wires 5 and 10 to the arm9. When the spherical mass leaves the hole 7 and moves onto the incline(the incline being shown at 14), the contact wire 5a, under theinfluence of its bias, moves toward the base and out of contact with thewire 10, see FIG. 3.

In the embodiment of FIG. 4, the base 4 is substituted in function forthe wire 10 so that the circuit is completed through the sphere 3, whichmust be conductive, from the base to the wire 50 when the sphere is inthe hole 7.

In operation, such as, but not limited to, automotive useage as aninertia switch for locking seat belt retractors, the inertia sensordescribed is mounted so as to be sensitive to acceleration force in thevehicle. As a result of a sufficient enough G force level, the mass 3moves from the hole up the incline breaking the electrical contact. Inone embodiment, the inertia sensor could beutilized to look a seat beltretractor on occurrences of such G force, as disclosed in' US. Pat. No.3,610,361, patented Oct. 5, 1971, for example.

The diameter of the hole and the angle of the incline will effect theforces necessary to move the mass against the forces of inertia andgravity out of the hole and up the incline. When such G forces havesufficiently declined or have disappeared, the mass will resettle in itsrest position in the hole.

Because the spherical mass has to move out of the hole a certaindistance before it no longer bears on contact arm 5, short durationpulses, such as caused by the effect of rough roads on an automobiledriving thereover on which the sensor is mounted, will not cause thebreaking of the contact between wires 5a and 10 in the sensor. There isinsufficient duration and intensity to move the mass 3 out of the holeand away from the wire 5, so as to release that wire from the wire 10.

In its operation as a sensor for an automobile, as previously described,the normal functioning state of the sensor will be as shown in FIG. 1,the sensor being normally mounted so as to be horizontal on line AA whenthe vehicle is horizontal.

Electrical contact will be had in that state between the wire 5a and thewire 10.'When sufficient G force for a sufficient duration occurs so asto move the mass from the hole up the incline, contact between wire 5aand the wire is broken, and the circuit will be broken causing, forexample, in the embodiment of the US. Patent cited above, the retractorto lock restricting movement of the passenger.

In the case of no net downward gravitational force in the mass, the wirepushes the mass upward thereby breaking the electrical contact. Such acase can occur during rollover, for example.

I claim:

1. An inertia switch comprising an insulative chamber formed by top,sidewalls and base having a hole therein, a freely movable masscontained within said chamber and larger in diameter than said hole soas to be removably positioned in said hole under rest conditions, saidchamber having inclined means for returning said mass to said positionin said hole, switch means including a movable biased wire electricalcontact underlying said hole mounted on said base for contacting aportion of said mass, said freely movable mass extending through saidhole when in said hole and contacting said wire, said switch meansmoving as a result of said contact with said mass in a direction againstits bias.

2. An inertia switch as claimed in claim 1, said switch means mountedoutside of said chamber and underlying said base, a portion of saidswitch means being contacted by said biased wire on said movement.

3. An inertia switch as claimed in claim 1, said switch means consistingof said base, said mass, said fixed contact and said biased wire, saidwireunderlying said hole.

1. An inertia switch comprising an insulative chamber formed by top,sidewalls and base haVing a hole therein, a freely movable masscontained within said chamber and larger in diameter than said hole soas to be removably positioned in said hole under rest conditions, saidchamber having inclined means for returning said mass to said positionin said hole, switch means including a movable biased wire electricalcontact underlying said hole mounted on said base for contacting aportion of said mass, said freely movable mass extending through saidhole when in said hole and contacting said wire, said switch meansmoving as a result of said contact with said mass in a direction againstits bias.
 2. An inertia switch as claimed in claim 1, said switch meansmounted outside of said chamber and underlying said base, a portion ofsaid switch means being contacted by said biased wire on said movement.3. An inertia switch as claimed in claim 1, said switch means consistingof said base, said mass, said fixed contact and said biased wire, saidwire underlying said hole.